Shock-proof circuit-breaker



H. J. SCHMID SHOCK PROOF CIRCUIT BREAKER.

APPLICATION FILED OCT-28, 1919. 1,355,511. Patented Oct. 12,1920.

2 SHEETSSHEET I.

INVENTOR.

HENRY-J: SCHM/D OR VEY H. J. SCHMID. SHOCK PROOF CIRCUIT BREAKER.

APPLICATION FILED OCT-28,1919- 1,355,511. Patented Oct. 12, 1920.

2 SHEETS-SHEET 2 R w N HENRY J: SCH NO.

UNITED STATES PATENT OFFICE.

HENRY J GEIN SCHMID, OF PHILADELPHIA, PENNSYLVANIA, .ASSIGNOR TO WILLIAM M. SCOTT, OF TREDYFFRIN TQWNSHIP, PENNSYLVANIA.

SHOCK-PROOF CIRCUIT-BREAKER.

Specification of Letters Patent.

Patented Oct. 12, 1920.

fl '0 all whom it may concern Be it known that I, HENRY J OHN SoHMID, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have in vented certain new and useful Shock-Proof Circuit-Breakers, of which the following is a specification.

lily invention relates to an electric switch or circuit breaker which is held in closed position by locking mechanism which may be released by automatic means or otherwise.

It is the object of my invention to provide switch or circuit breaker structure which shall withstand shocks or jars occasioned by forces acting upon the structure in or from various directions, without premature or undesired release of the restraining or locking mechanism.

My invention resides in switch or circuit brew 1' structure of the character referred to wherein the locking or restraining mechanism comprises a main lock or latch with which co-acts an auxiliary lock or latch to prevent release of the movable member of the switch or circuit breaker upon occurrence of shocks or jars, the auxiliary and main latches or locks being actuated in sucsession, the auxiliary lock or latch being first actuated and the main lock Or latch actuated by or through the auxiliary latch.

My invention resides further in shock proof switch or circuit breaker structure wherein the au--iliary latch or lock is pivoted upon the main lock or latch, which latter is preferably pivoted.

My invention resides in further features of structure and comblna ion hereinafter described and claimed.

I have preferred to illustrate my invenion by but one form, selecting one which is simple in construction and operation, highly practical, efficient and thoroughly trustworthy and reliable, and which at the same time well illustrates the principles of my invention.

Figure 1 is a side elevation, partly broken away, showing this preferred form of my invention. 7

Figs. 2, 8 and 4 are side elevations, partly sectioned showing some of the parts of Fig. 1 in different positions assumed during operation.

Fig. 5 is a bottom plan view of a portion of the structure seen in Fig. 1.

Fig. 6 is a top plan view and Fig. 7 a sideelevation of the latch actuator.

Fig. 8 is a top plan view and Fig. 9 is a side elevation of the main lock or latch.

Fig. 10 is a side elevation and Fig. 11 an end elevation, of the auxiliary latch or lock.

In various lines of electric activity, it is desirable to provide a switch which is normally closed against spring tension, as in the case of circuit breakers, or is sub ject to electromagnetic stresses tending to open it or which for some other reason must be locked in closed position to protect the circuit or circuits controlled by it, and which is subject to such jolts, ars or shocks that the locking mechanism must be protected against movement causing premature release.

Since such movements may be due to a single blow or to a series of blows in any dir ion, provision must be made to autoinaically reset the latch mechanism immediately, in case of any partial movement so as to protect the locking mechanism fully.

Referring to the drawing, 12 is a base or switchboard upon which are secured the main fixed contacts 13 and 13 adapted to he engaged and bridged by the movable laminated contact member 14 and thereby close the circuit, to be protected by the circuit breaker. The member 14 is secured at 1% to an arm 15 pivoted at 16 upon a fixed bracket or housing 17.

T he Switch operating arm 18 is pivoted at 19 in a fixed bracket, shown as the same bracket, ano is connected to actuate the arm 15 by a toggle lever 20 and a toggle link 21. @f these, 20 isrigid with the operating arm 18 and 21 is pivoted to the arm 20 at 22 and to the arm 15 at 23.

In the position shown, the toggle mechanism represented by lever 20 and link 21 is slightly under-traveled, 2'. 6., it i not thrown quite far enough for the center of the pivot at 22 to reach a line joining the centers of pivots 19 and 23. In this under-traveled position, the parts are given a normal tendency to open by a tension spring 24 which is secured at one end 25, to the arm 15 and at the other end to the operating arm 18, as at'26.

At a suitable position to cooperate with locking, latching and releasing mechanisms,

r of the bar 27 about the operating arm pivot hereinafter described, the operating arm carries a locking member in the form of a bolt or bar 27 which is shown here as comprising the transversely extending end of a strap 29. This strap and a strip 28 are secured to the operating arm conveniently by rivets 30. The strip 28 projects to limit the closing stroke of the operating lever by engagement of itsend 31 with some fixed surface32 such as the edge of bracket 17.

The locking mechanism, as shown, "cooperating with the bar 27, comprises two parts, an arm or carrier 33 for a stop 34:, constituting the main lock or latch, and a catch-arm 35 presenting a catch surface 36, and constituting the auxiliary look or latch. The stop-supporting arm or carrier 33 is pivoted at 37. to a fixed support, shown as bracket 17, and the catch arm 35 is pivoted upon the carrier 33, at some such point as 38. V

The 'st 0psupporting arm 33 is conveniently formed as a frame, having twoside walls 39 and 40 between which the stop 34:

is placed, the stop being, for example, a

roller mounted in the frame upon pivot 43. r The relation between the arc of movement point 19 and of the stop 34 about the pivot at 37 is such that the stop normally lies directly in thel'ine of movement of the bar in its arc of release movement indicated at 4:1; and the relation is further such that the contact between roller 34 and bar 21 lies substantially in a line passing through the centers of pivots 3'7-and'43.

The bar 27may be slightly canted counter clockwise with respect to a line joining the center of pivot 19 and the contact face of the bar, as shown,so that the tendency of the strain upon the operating-arm 18 shall be to seat the stop more firmly in looking position, or it may be turned slightly in a clockwise position, with respect to that shown, where the design is regarded as sutficiently safe to justify this changefor the :cates upward movement to tail 61 of the purpose of facilitating release of the stop from engagement with the bar.

In either event the face 4:2 of the bar should not depart far from a position of tangency'to are drawn through it about centers in the center of pivot 37 L For' convenience in construction and to make it more accessible for release tripping the pivot 37 for the carrier 33 is placed on that side of bar 27 toward the switch base 12; and the movement of thestop 3 s is most desirably upward from its inactive to its operative position. 7

The' stop carrier 33 is apertured at 3"? for pivot 37 and at 38 for pivot '38 and the catch arm 35 is 'apertured at .38" for a pivot 38 and at le to receive one. end of a spring/15 whose other end is secured at a fixed point 4st,

The relation between 38, l4: and 4: 1 is such that, in the position shown in Fig. 1, the aperture i l lies to the left of a line joining 38and l i and the spring isunder tension, holding the carrier 33 up and forcing the arm 35 in a clockwise direction on its pivot 38. This makes it possible to use the face 36 as a latch to maintain the arm 35 and, consequently,the carrier 33 andstop'34 in raised position, by engagingthis face with a relatively fixed surface.

The arm 35 thus performs the double function of lifting the carrier 33 and stop34: to'their operative positions and then holding them there until suitable release mechanism is operated. V

The latch face 36 is constantly and resiliently pressed in clockwise direction over the lock bar' 27 so as to take up or'regaln any counterclockwise movements which 'may have taken place due to jar and to correct and ofi set any tendency to cumulative rel'QRSlIlgBffGCt from repeated shocks.

lln e circuit breaker shown is provided wi h the usual solenoidalcoil @6, by which, when an excessive amount'of current passes through the coil, the armature a? is lifter.

The core 47 mav be adjusted, as usual, by means of a screw 4:8, lo'cked by nut 49, to

respond to different magnitudes of current.

Movable with the core 47 is the head 50 which, upon upward attraction of the core,

latch actuator or trip 62. The-latch actuator 62 is mounted between the sides 39, 10

of carrier 33 and is pivoted about the same center 3? as that about which the stop carrier turns so thatwith movementof tail 61' of the latch actuator an extension 63 there1 on is turned in a clockwise direction. The nose 64: upon this extension engages a shoulder 65 upon theauxiliary latch arm 35, turning this arm in counterclockwise direction against the tension of spring 45 and releas-,

ing the hold of the nose or overhang 36 of the latch arm upon the bar 27.

Whereas, from the 'standpomts of the locking and latching mechanisms the rollersupporting member 33 is properly called a stop carrier and the member 35 is properly called a latch arm, when these parts are considered from the standpoint of the tripping mechanism, as part of the tripping train, they may be properly considered as main and auxiliary triggers or latches.

Considered from this standpoint, counterclockwise movement of the auxiliary trigger latch 35. under the blow from the armature 47, through the latch actuator, proceeds without affecting the main trigger or latch until the heel 66 of the auxiliary trigger 35strikes the bottom 67 of the main trigger 33; at which time the blow is communicated to the main trigger 33 and causes clockwise movement of the main trigger, withdrawing the stop (roller) 34 from the path of move ment of the bar 27 upon operating arm 18. As soon as this occurs, the tendency of the operating arm to move in a counterclockwise direction under the influence of spring 24, results in opening the switch.

Several positions of the parts which need to be considered are shown in Figs. 1, 2, 3 and In Fig. 1 and in the dotted position in Fig. 2, the latch arm 35 is shown engaging the bar 27 and holding the stop carrier in raised position-so that the stop 34 prevents release movement of the bar 27 along its normal path of movement in the direction of the arrow and outlined by arc 41, the auxiliary latch preventing release of the main latch in response to shocks or jars.

When the latch actuator 62 has begun to lift, its nose 64 engages the shoulder 65, turning the latch arm, now considered as an auxiliary trigger, and releasing its face 36 from the bar 27.

As the spring 45 is under tension, there is no tendency to lower the stop carrier or the stop until the heel 66 of the auxiliary trigger strikes the bottom 67 of the stop carrier, now considered as a main trigger. This position is shown in full lines in Fig. 2.

Continued movement of the latch actuator 62 now causes clockwise movement of the stop carrier (main trigger) about the pivot 37 causing the stop 34 to pass below the lower arc of movement 41 of the bar 27 and the spring 24 immediately throws the operating arm 18 and opens the switch. An intermediate position of the parts during this switch opening movement is shown in Fig. 3 where the stop has been moved considerably out of the path of movement of the bar 27 and the bar has moved to the right through part of the switch opening movement of the arm.

As soon as the force of the armature blow is expended, the trigger parts come back to some such position relative to each other as that shown in Fig. 4 (intended to explain the resetting) where the spring 45 comes to rest'with the fastening at 44 in a direct line between the fastening at 44 and the pivot 38. Resetting movement of the switch op erating arm requires that the bar 27 during itsresetting movement in the d rection of the arrow in Fig. 4 shall engage the stop 34 above its center line, so that the stop and its carrier may be moved down sufliciently to permit the bar 27 to pass over it. At about the same time the bar 27 engages the latch arm 35 and forces it back. In the meantime the tension of spring 45 upon the latch arm, communicated to the stop carrier, causes the stop carrier to rise coincidently with the counter-clockwise movement of the latch arm 35 caused by pressure of the bar 27 against the latter. As a result, the stop 34 is lifted as soon as the bar 27 has passed it sufficiently to permit this lifting and, finally, the lifting of the stop and the swinging of the latch arm bring the latch face 36 above the bar 27 and the spring 45 causes it to snap over the latch bar, as shown in Fig. 1.

I claim- 1. In switch-locking mechanism, a movable contact member, an operating arm, in combination with means for blocking the re lease movement of the operating arm, movable in a direction across the path of the adjacent portion of the arm, and pivoted means carried by the first means for latching the latter in position.

2. In switch-locking mechanism, a movable contact member, an operating arm, in combination with a pivoted trigger movable into the path of release movement of the operating arm and receiving strain thereon in line with its pivot point, and an auxiliary trigger pivoted to and retaining the main trigger in operative position.

In switch-locking mechanism, a movable contact member, an operating arm, in combination with a main pivoted trigger adapted normally to lie in the line of release movement of the operating arm, means carried by the main trigger for retaining it in this position, and common spring means for normally holding the trigger and auxiliary means in operative position.

4. In switch-locking mechanism, a mov able contact member, an operating arm, a main trigger pivoted near one end and having a part adapted to swing into the path of release movement of the operating arm and to receive strain in line with its pivot point, a latch pivoted to the main trigger between the point of engagement of the operating arm and the pivotpoint, means for raising the main trigger and holding the latch in position, and a release trip for the latch engaging it to release the latch and to throw the main trigger.

5. In locking mechanism for switches, a movable switch contact member, an operating arm, and a locking bar carried by the operating arm and having a path of release movement, in combination with a pivoted trigger curing release movement,

trigger adapted to enter said path to hold the locking bar in position, a pivoted latch carried by the trigger adapted to engage the locking bar to retain thetrigger in position, and release means for operating the latch first and the trigger'subsequently.

6. In locking mechanism for switches, a movable switch contact member, an operating arm, and a locking bar carriedby the operating arm and having a path ofrelease movement, in combination with a pivoted trigger, a roller carried by the trigger adapted to enter said path to engage the locking bar and retain the operating arm in switch-closing position, a latch carried'by the trigger and engaging it to swing the spring means for setting the latch, and a trip for the latch and trigger.

7. In switch-locking mechanism,-a mov- 'able contact member, an operating arm, a

main trigger pivoted near one end and having a part adapted to' swing into the path of release movement of the operating arm and to receive strain in line with its pivot point,

a spring-supported latch on the trigger normally holding it in'lock-ing position and engaging it in release movement of the latch,

and tripping means for the latch communicatin with the trigger throughthe latch.

8. n a locking mechanism for automatic switches,a movable switch contact member,

a switch-operating lever, and a locking bar' thereon adapted to move in a curved path in combination with a swinging look for the bar adapted to 'move into the path of movement of the bar, and a latch, for the lock adapted to extend above the bar and engage it. I 7

9. In switch-locking mechanism, a movable switch contactmember and an operatinglever having a bar thereon adapted to move in acurved path, in combination with a swinging locktherefor movable into the path of movement of the bar and receiving.

strain therefrom in line with the point of support of the lock, and swinging latch for the lock, swinging initially in the opposite direction and subsequently swinging With the lock. V

'10. In switch-locking mechanism, a movable switch contact member and an operating lever, in combination with an up wardly swinging lock engaging the operating lever, and a latch holding the swinging lock in lifted position and having initial lateral engaging and release movement.

11. In switch-locking mechanism, a movable switch contact member and an operating lever having a locking member connected therewith, in combination with a locking device movabl'efinto the pathfoi' 're- I leasemovementof thelocking member, and

a'lat'ch supported on the locking device and spring-raised to hold the'locking device in 7 switch member.

locking position andthe latch in latched" position. 1 i

. 12. T he combinatlonwith a movable member of anelectric swltch, of HliLlILlOCli therefor comprising a pivoted member, a

roller'pivotedthereon and engaging said switch member to restrain the same in'norclocking trig er movable into the oath of b J.

movement of the locking bar, a latch pivoted to the trigger, and a spring fixed at one end and secured to the latch at the other end out of the llne JOlIllIlg its fixed end and thelatch pivot to lift the trigger through the latch and to throw the latch laterally to engaging position. i

15. In locking mechanism for switches, a

movable switch contact member, an operr.

ating arm, and a locking bar carried by the operating arm and having a path of release movement, in combination with. a main locking trigger movable'into the path of release movement of the locking bar, an auxiliary trigger adapted to latch the locking trigger in'said position and to throw the main trigger, and a trip adapted to release the auxiliary trigger and through it the main trigger.

16. In locking mechanism for switches,

'a movable switch contact member, an operating arm, and a locking bar carried by the operating arm and having a path of release 'move'ment, in combination with a pivoted main trigger adapted to, move into the path of release movement of the locking bar, .an auxiliary triggermounted thereon, means for maintaining the main and auxiliary.

triggers in,lockingposition, a trippivoted at approximately the same point as'the main trigger and adapted to release the auxiliary trigger, and automatic means for actuating" the trip.

17. In locking mechanism for switches, a movable switch contact member, an oper-. ating arm, and a locking bar carried by the operating arm and having a path of release movement, 4 in combination with a main trigger adapted to move into locking en-' V gagement in the [path of release movement of'the locking bar, an auxiliary trigger thereon acting as a latch to hold the main trigger in looking position and having a heel adapted for engagement with the main trigger, and an automatic trip for the auxiliary trigger moving the auxiliary first and through it the main trigger.

18. In locking mechanism for switches, av movable switch contact member, an operating arm, and a locking bar carried by the operating arm and having a path of release movement, in combination with a main tri ger adapted to swing into the path of movement of the locking bar, an auxiliary trigger adapted to swing upon the main trigger and to support it, spring means for holding the auxiliary trigger in position, supporting also the main trigger, and automatic means for tripping the auxiliary trigger first and subsequently the main trigger through the auxiliary trigger.

19. In locking mechanism for switches, a movable switch contact member, an operating arm, and a locking bar carried by the operating arm and having a path of release movement, in combination with a main trigger pivoted to swing into locking engagement with the locking bar of the operating arm, an auxiliary trigger pivoted to the main trigger and adapted to latch over a relatively fixed member in one direction of movement and to-engage the main trigger in the opposite direction of movement, and

a spring normally holding the auxiliary trigger in latching position.

20. In locking mechanism for switches, a

movable switch contact member, an operating arm, and a locking-bar carried by the operating arm and having a path of release movement, in combination with a main trigger pivoted to swing into locking engagement with the locking bar of the operating arm, an auxiliary trigger pivoted to the main trigger and adapted to latch over a relativelv fixed member in'one direction of movement and to engage the main trigger in the op osite direction of movement, a spring normally holding the auxiliary trig ger in latching position, and atrip engaging the auxiliary trigger to unlatch it and to subsequently release the main trigger.

21. In locking mechanism for switches, a movable switch contact member, an operating arm, and a locking bar carried by the operating arm and having a path of release movement, in combination with a main trigger pivoted to swing into locking engagement with the locking bar of the operating latching position, a trip engaging the auxiliary trigger to unlatch it and to subselatch to release it, the latch subsequently engaging the trigger to move it out of its normal position, and current-operated means for actuating the trip.

23. Trigger mechanism for the operating arm of an automatic switch comprising a main trigger pivoted near one end and near the other end adapted to be engaged by the switch-operating arm, and an auxiliary trigger pivoted to said main trigger and acting as a latch.

24:. The combination with a base, of a movable member of a switch carried thereby, and locking mechanism for said movable member comprising a locking member pivoted to said base, a roller carried by said locking member and engaging said movable switch member, and a latch carried by and movable with respect to said locking member.

25. Trigger mechanism for switch-operating arm retention comprising a main trigger adapted to be pivoted near one end, a roller carried thereby for retention of the operating arm, and a latch carried'by the trigger, having initial release movement opposite in direction to the release movement of the trigger and subsequently engaging the main trigger to move it in an opposite direction.

26. Trigger mechanism for switch-operating arm retention comprising a trigger adapted to be pivoted at one end and having channel form, a roller mounted within the channel near the opposite end thereof and adapted to come within the path of movement of the operating arm, and a latch pivoted within the channel and adapted to lie generally over the roller for engagement with the operating arm.

27. Trigger mechanism for switch-operating arm retention comprising a trigger adapted to be pivoted at one end and having channel form, a roller mounted within the channel near the opposite end thereof and adapted to come within the path of movement of the operating arm, a latch pivoted to extend within the channel, and

. a trip for the latch pivoted at the pivot point channel near the opposite end thereof and adapted to come within the path of m vement of the operating arm, and a latch pivoted within the'channel, adapted to lie generally overthe roller for engagement'with V .the operating arm and in release movement to engage the bottom of the channel and actuate the trigger. s

29. The combination with a base, of a 'movable switch member carried thereby, a

main latch carried by'said base and engaging said switch member, and means for restraining said main latch Comprising an auxiliary latch pivoted on said main latch;

30. The combination with a base, ot a movable switch member carried thereby, a main latch pivoted to said base and engaging said switch member,- and means for restraining said main latch comprising an auxiliary latch pivoted on'said main latch.

31. The combination with a base, of 'a' v movable switch member carriedthereby, a

main latch carried by said base and engaging said switch member, and an auxiliary latch pivoted on'sald main latch and engaging said switch member.

roller pivoted thereon and engaging said switch member to restrain the same in normal position, means for preventing actua-- 32. The combination with a base, of a movable switch member carried thereby, a

main latch pivoted to said base and engaging said switch member, .and an auxiliary latchpivoted on said main latch and engaging said switch member.

The combnation w'th a movable memberof an electric switch, of a main lock therefor comprising a pivoted member, a

tion of said main look by shock or'jar comber of a switch, of a main latch for restrainprising an auxiliary latch pivoted on said pivoted member and engaging said switch member, and a latch actuator for actuating saidhpivoted member through said auxiliary latc 34. The combination with a movable meming the same in normal position, means for locking said main latch comprising an aux iliary latch pivoted on said main latch, and a latch actuator for actuat ng said auxll ary latch and main latch in succession. 7 35.1The combination with a base, of a movable member of a s'witch 'carried thereby, and locking mechanism for said movable member comprising a locking member pivoted to said base, a roller carried by said locking member and engaging said movable switch member, a latch carried by and movable with respect to said locking member,

and a latch actuator for actuating said locking member through said'latch.

36. The combination with a base, of a movable switch member carried thereby, a main latch 'ca'rried by said base and engaging said vSwitch member, means for restrain ing said main latch comprising an auxiliary latch pivoted on said main latch, and a 'latch actuator ioractuating said auxiliary latch and thereafter said main latch.

37. The combination with a base, of a movable switch member carried thereby, a main latch. pivoted to said base and engaging said switch member, means for locking said main latch comprising an auxiliary latch pivoted on said main latch, and a- 'latch actuator for actuating said main latch through said auxiliary latch.

88. The combination with a base, of a movable switch member carried therebyfa main latch carried by said base and engaging said switch member, an auxiliary latch pivoted on said main latch and engaging said switch member, and a latch actuator for actuating said auxiliary latch and through 40. The combination with a movable member of an electric switch, of a main lock therefor comprising a pivoted member, a roller pivoted thereon and engaging said switch member to restrain the same innormal position, means for preventing actuation of saidmain lock by shock or jar comprising an auxiliar latch pivoted onsaid member, and a spring opposing release of said auxiliary latch and through it opposing release of said pivoted member.

41. The combination with a movable member of a switch, of a main latch for restrainingthe same in normal positiorn'means for locking said main latch comprising an auxiliary latch pivoted on said main latch, and

a spring'att'ached .to said auxiliary latch controlling the same and said inainlatch.

42. The combination with a base, of a movable member of a switch carriec'l there- ;by, and locking mechanism for saidmovable' member comprising a locking member pivoted to said base, a roller carried "by said "locking member and engaging said movable switch member, means for restraining said locking member comprising a latch carried by and movable with respect to said locking member, and a spring attached to said base 7ind through said latch to said locking mem- 43. The combination with a base, of a movable switch member carried thereby, a

.main latch carried by saidbase and engaging said switch'member, means for locking said main latch in locking position comprising an auxiliary latch pivoted on said pivoted member and engaging said switch main latch, and a spring attached to said base and to said auxiliary latch.

44:. The combination with a movable member of a switch, of a main latch for restrain= ing the same in normal position, means for lockin said main latch comprising an auxiliary latch pivoted on said main latch, a latch actuator for actuating said auxiliary latch and main latch in succession, and a spring opposing said actuator connected to said auxiliary latch.

45. The combination with a base, of a movable switch member carried thereby, a

' main latch pivoted to said base and engaging said switch member, an auxiliary latch pivoted on said main latch and engaging said switch member, a latch actuator for actuating said main latch through said auxiliary latch, and a spring opposing said actuator connected to said base and to said main latch through said auxiliary latch.

Q6. The combination with a base, of a movable member of a switch carried thereby, a main latch carried by said base and engaging said switch member, means for locking said main latch comprising an auxiliary latch carried by and movable upon said main latch, and a spring connected to said main latch through said auxiliary latch.

47. The combination with a base, of a movable member of a switch carried thereby, a main latch carried by said base and engaging said switch member, an auxiliary latch engaging a member other than said main latch and carried by and movable upon said main latch, and a latch actuator for actuating said main latch through said auxiliary latch.

48. The combination with a base, of a movable member of a switch carried thereby, a main latch carried by said base and engaging said switch member, an auxiliary latch engaging a member other than said main latch and carried by and movable upon said main latch, a latch actuator for actuating said main latch through said auxiliary latch, and a spring opposing said actuator connected to said auxiliary latch and through it to said main latch.

49. The combination with a base, of a movable member of a switch carried thereby, a main latch carried on said base and engaging said switch-member to restrain the same in normal position, and means for locking said main latch comprising an auxiliary latch engaging a member other than said main latch and carried by said main latch.

HENRY JOHN SCHMID. 

